WEDNESDAY, July 12, 2017 (HealthDay News) -- People of the world, step it up!

A new global study finds that countries that have large differences in walking rates among citizens have higher levels of obesity than countries that don't see such a spread, a new study finds.

It included 717,000 people in 111 countries whose walking levels were tracked using smartphones for an average of 95 days.

"If you think about some people in a country as 'activity rich' and others as 'activity poor,' the size of the gap between them is a strong indicator of obesity levels in that society," said study co-leader Scott Delp, a bioengineer at Stanford University.

The United States ranked fourth from the bottom in overall activity inequality, indicating a large gap between activity rich and activity poor. Meanwhile, it had high levels of obesity, Delp's team found.

The researchers also found that gender was a significant factor in country-to-country differences. As in previous studies, this one found that men walk more than women. But the researchers found that this gender gap varied from country to country.

"When activity inequality is greatest, women's activity is reduced much more dramatically than men's activity, and thus the negative connections to obesity can affect women more greatly," study co-leader Jure Leskovec, a computer scientist at Stanford, said in a university news release.

The researchers said they hope their findings will help shape public health campaigns that tackle obesity and support policies to make cities more "walkable."

The study was published July 10 in the journal Nature.

Each year, about 5.3 million people worldwide die from causes linked with physical inactivity, the researchers noted.